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Member (Idle past 2519 days) Posts: 2965 From: Los Angeles, CA USA Joined: |
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Author | Topic: Archaeopteryx and Dino-Bird Evolution | |||||||||||||||||||||||
arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
I think arach was trying to say that velociraptor has long arms compared to the legs. just like birds today--except birds have even longer arms compared to their legs (I think) flying birds, yes. flightless birds tend to be much shorter, but the evidence is that they evolved from flying birds (though, i believe, there are some crazies that suspect paleognaths came straight from dinos). anyways, longer arms is evidence of avian tendencies.
t-rex would have a very short arm to leg ratio--short arms compared to the legs. the shortest, actually. except maybe mononykus, but i can never get a straight answer on whether or not that's a chimera. dromaeosaurs and troodondits have the longest arms, and archaeopteryx holds the record, with arms and legs equal in length. velociraptor has the longest arms of any dinosaurs that's not actually a bird, iirc.
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arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
The Solnhofen Limestone is the remnant of that lagoon bottom I mentioned earlier. All seven known Archaeopteryx fossils came from it. eight if you count the feather.
And it didn't get deposited in a giant forty-day flood, either. one year flood.
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Cthulhu Member (Idle past 5879 days) Posts: 273 From: Roe Dyelin Joined: |
Synapsids aren't reptiles, because Reptilia has been redefined to fit into cladistics.
It looks like the following.
-Amniota |_ |-Synapsida |-Sauropsida |-Something or another |-Reptilia |-modern reptiles
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Cthulhu Member (Idle past 5879 days) Posts: 273 From: Roe Dyelin Joined: |
The preserved skin portions are on the legs and the underside of the tail, which are not exactly places where feathers need to be. Now, if skin impressions were found on the arms or back, then it would be a reasonable assumption that Juravenator was featherless.
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arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
Synapsids aren't reptiles, because Reptilia has been redefined to fit into cladistics. there is no "reptilia." it's sauropsida. sauropsids and reptiles are synonymous, and the term "reptile" was actually discarded in terms of cladistics some time ago, because dinosaurs abd birds (sauropsids) don't fit especially with the connotation of "reptile."
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arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
The preserved skin portions are on the legs and the underside of the tail, oh, ok, i must have missed that. we know there was secondary feather loss on the feet, because of genetics.
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Cthulhu Member (Idle past 5879 days) Posts: 273 From: Roe Dyelin Joined: |
I know Sauropsida is the larger grouping. The last I checked, Reptilia had been redefined as a daughter group of Sauropsida.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3 |
The preserved skin portions are on the legs and the underside of the tail, which are not exactly places where feathers need to be. Now, if skin impressions were found on the arms or back, then it would be a reasonable assumption that Juravenator was featherless. Indeed. But, Arachnophilia stated all the skin impressions we had showed feathers. This is not so.
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arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
yes, yes, i was unaware of that find. but thanks for pointing it out.
do you think this rules out the dinosaur having feathers? just complicates the matter? any particular take on this? it's rather peculiar that other closely related dinosaurs (both branching lower and higher on the tree, cladistically) did have feathers.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3 |
I think the most parsimonious explanation is that Juravenator has undergone selective feather loss across some parts of its body and a more complete skin print would reveal this.
But I also think it's important to differentiate between what we can observe and what we can deduce.
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arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
But I also think it's important to differentiate between what we can observe and what we can deduce. well, the thing is this. we know that at some point dinosaurs/birds lost some feathers. the earliest flying dinosaurs we have are "four-winged," with flight feathers on their feet. genetically, we know that modern bird scutes evolved from feathers. so the question i'm really asking is, is it safe to say that juravenator probably had feathers, and this secondary feather adaptation? i'm not sure, they note that the skin lacks the follicles for feathers. it might an age/gender thing? or maybe the simplest deduction is that feathers are convergent. [or reccessive?] Edited by arachnophilia, : added bracket
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arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
more info:
quote: hmm.
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Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 8.3 |
I think the article you quoted answered the question better than I can.
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arachnophilia Member (Idle past 1371 days) Posts: 9069 From: god's waiting room Joined: |
yeah, i got curious, and googled. i still don't quite know what to make of it. very peculiar.
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Archer Opteryx Member (Idle past 3625 days) Posts: 1811 From: East Asia Joined: |
S1WC: Exactly! That's why I hold to the position that the more distinct specimens with feather imprints are fruad! My point! Reptiles don't have feathers! But engraving them wouldn't be too hard, and it pays well in the museums for a "transitional fossil." It may interest you to know that the Archaeopteryx fossils are regarded as genuine even by the hard-core creationists at Answers in Genesis. They list your 'hoax' assertion near the top of their Arguments we think creationists should NOT use. Archer All species are transitional.
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